1. Field of Invention
The present invention relates to a lamp, and more particularly to an electrodeless fluorescent lamp having a ventilation channel which is adapted to remove most of the heat from a heating coil of the electrodeless fluorescent lamp.
2. Description of Related Arts
Electrodeless fluorescent lamp was discovered 100 years age by Hittorf. Since then, hundreds of patents and all kinds of electrodeless lamps have been filed and developed. However the functions of these electrodeless lamp and systems are still not very good yet.
Referring to FIG. 1 of the drawings, a conventional electrodeless induction-coupled fluorescent lamp 1P is illustrated. The electrodeless induction-coupled fluorescent lamp 1P comprise a glass vessel 10P which encloses a predetermined amount of mercury vapor and a buffer gas or gases and a phosphor or a phosphor with protection coating, a reentrant channel 20P, a heating coil 30P, an optional ferrite 40P, a metal rod 50P, a metal base 60P and a glass vessel support 70P. The heating coil 30P generates RF energy and induction-coupled plasma producing Ultra-Violet (UV) light inside the glass vessel 10P. The phosphor converts the UV to visible light. The metal rod 50P removes the heat from the heating coil 30P through the glass vessel support 70P.
U.S. Pat. No. 5,105,122 of Konings et al discloses another kind of electrodeless induction-coupled fluorescent lamp, in which the lamp comprises a glass vessel, a coil, a ferrite rod, and a base. The heat generated by the coil and the plasma is conducted out through the ferrite rod, which is not a good thermal conductor. This lamp has a higher temperature at the coil and cavity. Therefore the lamp has higher loss and low operation efficiency.
U.S. Pat. No. 5,355,054 of Lierop et al yet discloses another type of electrodeless induction-coupled fluorescent lamp which has a similar structure as shown in FIG. 1 of the drawings. The central rod is replaced by a cooling body, which is gas tight. The cooling body includes a condenser, an evaporator, a liquid, and a capillary structure. The liquid cooling system very efficiency, very expansive, and relatively complex in construction. Because of the limited space, this cooling system only can remove limited heat from the coil and the plasma to the base. This lamp still has a higher temperature at the coil and cavity. Therefore the lamp has higher loss and low efficiency.
U.S. Pat. No. 5,572,083 of Antonis at el. discloses another type of electrodeless induction-coupled fluorescent lamp which comprises a glass vessel, a coil, a ferrite, a rod, and a base. The heat generated by the coil and the plasma is conducted out through the rod. Because of the limited space, the size of the rod is limited. The rod only can remove limited heat from the coil and the plasma to the base. This lamp still has a higher temperature at the coil and cavity. Therefore the lamp has higher loss and low efficiency.
U.S. Pat. Nos. 5,621,266 and 5,723,947, both of Popov at el., disclose another type of electrodeless induction-coupled fluorescent lamp which comprise a glass vessel, a coil, a metal pipe, and a base or fixture. The heat generated by the coil and the plasma is conducted out through the metal pipe. Because of the limited space, the thickness of the metal pipe is limited. The metal pipe only can remove limited heat from the coil and the plasma to the base or the fixture. This lamp still has a higher temperature at the coil and cavity. Therefore the lamp has higher loss and low efficiency.
U.S. Pat. No. 6,081,070 of Popov at el. discloses another type of electrodeless induction-coupled fluorescent lamp which comprises a glass vessel, a coil, a ferrite core, a metal pipe, and a base or fixture. The heat generated by the coil and the plasma is conducted out through the ferrite core and the metal pipe. Because of the limited space, the thickness of the metal pipe is limited. The metal pipe only can remove limited heat from the coil and the plasma to the base or the fixture. This lamp still has a higher temperature at the coil and cavity. Therefore the lamp has higher loss and low efficiency.
U.S. Pat. No. 6,555,954 of Chandler at el. discloses another type of electrodeless induction-coupled fluorescent lamp which comprises a glass vessel, a coil, a ferrite core, a metal pipe, and a base or fixture. The heat generated by the coil and the plasma is conducted out through the ferrite core and the metal pipe. Because of the limited space, the thickness of the metal pipe is limited. The metal pipe only can remove limited heat from the coil and the plasma to the base or the fixture. In this patent, the glass vessel was glued to the base to get better heat sink. However, the base size is limited and removing additional heat is limited. This lamp still has a higher temperature at the coil and cavity. Therefore the lamp has higher loss and low efficiency.
All the above-mentioned arts utilize a metal rod or pipe to conduct (i.e. remove) heat from the center of the lamp to the base or to the outside. However, because of structure limitation, this kind of heat reduction mechanism is certainty not good enough to adequately reduce the temperature of the coil and the glass vessel.